logger: move _writer.lock() call after write_changed_parameters()

write_changed_parameters() also takes the lock and thus would deadlock
otherwise.

src/modules/logger/logger.cpp

@@ -476,8 +476,6 @@ void Logger::run()
 		}
 
 		if (_enabled) {
-			/* wait for lock on log buffer */
-			_writer.lock();
 
 			bool data_written = false;
 
@@ -492,6 +490,9 @@ void Logger::run()
 			// Write data messages for normal subscriptions
 			int msg_id = 0;
 
+			/* wait for lock on log buffer */
+			_writer.lock();
+
 			for (LoggerSubscription &sub : _subscriptions) {
 				/* each message consists of a header followed by an orb data object
 				 */